Implemented Make Carol Ann OD2 great again :)

TGM

TGM

Inspired
Hi,

OD2 is my favourite amp in the unit, which happily pushed me to buy the real amp. Therefore I am very well accustomed to the signature singing-warm Carol Ann midrange.

Even though the amp sounds great with Cygnus, I think it lost some of it signature mid range. It is just a bit colder now, a bit closer to the Mesa camp. I am really talking about miniature nuances here, so I don't mean it sounds completely the same with a Mesa.

Please Cliff, compare the Cygnus version with the real amp, and bring back the warmer-singing Carol Ann mids.
 
One thing I noticed about this and the Bludojai, if the headroom meter is to be believed, is that the ODS amps in general seem to run out of headroom at very low MV levels now. I assume that this is not a bug, but a reflection of truer tapers.

Maybe try getting the headroom down closer to what it was before will get you closer to what it was? AFAIK, Dumble amps were really meant to have overdrive come from the preamp, not the power amp.
 
I looked into this and found the problem. When I originally ran the calculations I had the wrong tube type for the phase inverter. I used a 12AT7 instead of a 12AX7A. This results in wrong default negative feedback. The correct value is 3.70. Sound much better with that value. In fact sounds so good I spent the rest of the night just playing (when I should've been working).

If you want to smooth things out further and get more midrange push increase the transformer matching by about 20%. The real amp is very "open" as the output transformer is undermatched by about 20%.
 
I'm really grateful to have the Carol Anns in the box. I fell in love with the Tucana years ago from the Axe model, and was able to get a real one- and I love the Triptik and OD2 as well. They're really special amps. I'm glad that Alan has a design being sold - the CAZ Dr. Z collaboration amp, which looks like a monster, btw.
 
FractalAudio said:
I looked into this and found the problem. When I originally ran the calculations I had the wrong tube type for the phase inverter. I used a 12AT7 instead of a 12AX7A. This results in wrong default negative feedback. The correct value is 3.70. Sound much better with that value. In fact sounds so good I spent the rest of the night just playing (when I should've been working).

If you want to smooth things out further and get more midrange push increase the transformer matching by about 20%. The real amp is very "open" as the output transformer is undermatched by about 20%.
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Oh I just saw this. Thank you so much Cliff.
Just for another feedback to you. Another amp I use very regularly is ODS HRM, and i think with the new release it has a similar issue to the OD2. It would be great if you could check that one too.
 
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Adman103 said:
I'm really grateful to have the Carol Anns in the box. I fell in love with the Tucana years ago from the Axe model, and was able to get a real one- and I love the Triptik and OD2 as well. They're really special amps. I'm glad that Alan has a design being sold - the CAZ Dr. Z collaboration amp, which looks like a monster, btw.
Click to expand...
And he mentioned in a forum there will be more coming from their collab. I’m really excited for that.
 
FractalAudio said:
If you want to smooth things out further and get more midrange push increase the transformer matching by about 20%. The real amp is very "open" as the output transformer is undermatched by about 20%.
Click to expand...
Hi Cliff,

To do that should I set the Mismatch parameter in the power tubes section to 0.2? Or are you referring to another parameter? And should that be + or - 0.2?
 
androtaz said:
Hi Cliff,

To do that should I set the Mismatch parameter in the power tubes section to 0.2? Or are you referring to another parameter? And should that be + or - 0.2?
Click to expand...
You’re looking for the Transformer Match (XFMR Match) parameter. Increasing that parameter by 20% means making its value 20% higher.
 
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